Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 39,490
  • Total confirmed cases: 5,989
  • Deaths from Confirmed Cases: 1,095
  • Case Fatality Ratio: 20%
  • Number of Health Care Workers: 232

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 12

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 3,468 suspected cases were reported from 1 in Akwa Ibom, Jigawa, Katsina to 1,083 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 31% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 18% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 12, 87% of LF cases are from Ondo (29%), Bauchi (25%), Edo (16%), and Taraba (16%) States.

  • Total confirmed cases: 645

  • Deaths from Confirmed Cases: 119

  • Case Fatality Ratio: 18%

  • Number of Health Care Workers: 20

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 12 2025, cumulatively 645 cases and 119 deaths (CFR=18%) across 18 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 31% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 18% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 36 States had reported at least one suspected case versus 33 States in 2025 to date.
    • 27 States had reported at least one confirmed case versus 18 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 12


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 2 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Ebonyi.

  • As of epi week 12 of 2025, there has been 20 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 12)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 926 190 23 12%
2024 1028 184 13 7%
2023 1046 262 30 11%
2022 616 193 34 18%
2021 252 61 18 30%
2020 451 299 43 14%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 190 confirmed cases including 23 deaths (CFR 12%).
  • Compared to same period 2024, this represents:
    • 10% decrease in the number of suspected cases.
    • 3% increase in the number of confirmed cases.
    • 71% increase in CFR.




  • In 2024 as of week 12:
    • 1028 in the number of suspected cases.
    • 184 in the number of confirmed cases.
    • 13 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 12:
    • 1046 in the number of suspected cases.
    • 262 in the number of confirmed cases.
    • 30 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 12:
    • 616 in the number of suspected cases.
    • 193 in the number of confirmed cases.
    • 34 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 12:
    • 252 in the number of suspected cases.
    • 61 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 30% average CFR.




  • In 2020 as of week 12:
    • 451 in the number of suspected cases.
    • 299 in the number of confirmed cases.
    • 43 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 659 161 12 7%
2024 564 123 27 22%
2023 594 92 15 16%
2022 583 102 10 10%
2021 36 7 2 29%
2020 251 41 17 41%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 161 confirmed cases including 12 deaths (CFR 7%).
  • Compared to same period 2024, this represents:
    • 17% increase in the number of suspected cases.
    • 31% increase in the number of confirmed cases.
    • 66% decrease in CFR.




  • In 2024 as of week 12:
    • 564 in the number of suspected cases.
    • 123 in the number of confirmed cases.
    • 27 in the number of deaths.
    • 22% average CFR.




  • In 2023 as of week 12:
    • 594 in the number of suspected cases.
    • 92 in the number of confirmed cases.
    • 15 in the number of deaths.
    • 16% average CFR.




  • In 2022 as of week 12:
    • 583 in the number of suspected cases.
    • 102 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 10% average CFR.




  • In 2021 as of week 12:
    • 36 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.




  • In 2020 as of week 12:
    • 251 in the number of suspected cases.
    • 41 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 41% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 1083 105 16 15%
2024 1178 178 23 13%
2023 1407 238 31 13%
2022 1088 164 21 13%
2021 852 102 12 12%
2020 980 306 39 13%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 105 confirmed cases including 16 deaths (CFR 15%).
  • Compared to same period 2024, this represents:
    • 8% decrease in the number of suspected cases.
    • 41% decrease in the number of confirmed cases.
    • 18% increase in CFR.




  • In 2024 as of week 12:
    • 1178 in the number of suspected cases.
    • 178 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 12:
    • 1407 in the number of suspected cases.
    • 238 in the number of confirmed cases.
    • 31 in the number of deaths.
    • 13% average CFR.




  • In 2022 as of week 12:
    • 1088 in the number of suspected cases.
    • 164 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 13% average CFR.




  • In 2021 as of week 12:
    • 852 in the number of suspected cases.
    • 102 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 12% average CFR.




  • In 2020 as of week 12:
    • 980 in the number of suspected cases.
    • 306 in the number of confirmed cases.
    • 39 in the number of deaths.
    • 13% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 247 103 31 30%
2024 190 95 20 21%
2023 206 73 25 34%
2022 70 29 14 48%
2021 46 18 11 61%
2020 89 54 21 39%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 103 confirmed cases including 31 deaths (CFR 30%).
  • Compared to same period 2024, this represents:
    • 30% increase in the number of suspected cases.
    • 8% increase in the number of confirmed cases.
    • 43% increase in CFR.




  • In 2024 as of week 12:
    • 190 in the number of suspected cases.
    • 95 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 21% average CFR.




  • In 2023 as of week 12:
    • 206 in the number of suspected cases.
    • 73 in the number of confirmed cases.
    • 25 in the number of deaths.
    • 34% average CFR.




  • In 2022 as of week 12:
    • 70 in the number of suspected cases.
    • 29 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 48% average CFR.




  • In 2021 as of week 12:
    • 46 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 12:
    • 89 in the number of suspected cases.
    • 54 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 39% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 99 19 9 47%
2024 213 43 24 56%
2023 160 49 27 55%
2022 180 37 17 46%
2021 75 15 6 40%
2020 149 67 16 24%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 19 confirmed cases including 9 deaths (CFR 47%).
  • Compared to same period 2024, this represents:
    • 54% decrease in the number of suspected cases.
    • 56% decrease in the number of confirmed cases.
    • 15% decrease in CFR.




  • In 2024 as of week 12:
    • 213 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 56% average CFR.




  • In 2023 as of week 12:
    • 160 in the number of suspected cases.
    • 49 in the number of confirmed cases.
    • 27 in the number of deaths.
    • 55% average CFR.




  • In 2022 as of week 12:
    • 180 in the number of suspected cases.
    • 37 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 46% average CFR.




  • In 2021 as of week 12:
    • 75 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2020 as of week 12:
    • 149 in the number of suspected cases.
    • 67 in the number of confirmed cases.
    • 16 in the number of deaths.
    • 24% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 63 15 4 27%
2024 94 28 2 7%
2023 34 11 1 9%
2022 96 37 6 16%
2021 5 1 0 0%
2020 73 33 8 24%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 33% decrease in the number of suspected cases.
    • 46% decrease in the number of confirmed cases.
    • 273% increase in CFR.




  • In 2024 as of week 12:
    • 94 in the number of suspected cases.
    • 28 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 12:
    • 34 in the number of suspected cases.
    • 11 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 9% average CFR.




  • In 2022 as of week 12:
    • 96 in the number of suspected cases.
    • 37 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 16% average CFR.




  • In 2021 as of week 12:
    • 5 in the number of suspected cases.
    • 1 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 12:
    • 73 in the number of suspected cases.
    • 33 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 24% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 55 12 6 50%
2024 25 3 1 33%
2023 29 6 0 0%
2022 101 15 6 40%
2021 3 0 0 –
2020 23 7 2 29%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 12 confirmed cases including 6 deaths (CFR 50%).
  • Compared to same period 2024, this represents:
    • 120% increase in the number of suspected cases.
    • 300% increase in the number of confirmed cases.
    • 50% increase in CFR.




  • In 2024 as of week 12:
    • 25 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 12:
    • 29 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 12:
    • 101 in the number of suspected cases.
    • 15 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 40% average CFR.




  • In 2021 as of week 12:
    • 3 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 12:
    • 23 in the number of suspected cases.
    • 7 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 29% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 12:
Years Suspected cases Confirmed cases Deaths CFR
2025 40 9 4 44%
2024 999 62 11 18%
2023 131 36 3 8%
2022 188 30 8 27%
2021 13 3 0 0%
2020 21 8 3 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 9 confirmed cases including 4 deaths (CFR 44%).
  • Compared to same period 2024, this represents:
    • 96% decrease in the number of suspected cases.
    • 85% decrease in the number of confirmed cases.
    • 151% increase in CFR.




  • In 2024 as of week 12:
    • 999 in the number of suspected cases.
    • 62 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 18% average CFR.




  • In 2023 as of week 12:
    • 131 in the number of suspected cases.
    • 36 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 8% average CFR.




  • In 2022 as of week 12:
    • 188 in the number of suspected cases.
    • 30 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 27% average CFR.




  • In 2021 as of week 12:
    • 13 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 12:
    • 21 in the number of suspected cases.
    • 8 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 38% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon